Good friends in real life, Fred Allen and Jack Benny inadvertently hatched a running gag in 1937, when a child prodigy, violinist Stuart Canin, gave a very credible performance on the Allen show, inspiring an Allen wisecrack about "a certain alleged violinist," who should hide in shame over his poor playing. Allen often mentioned his show-business friends on the air ("Mr. Jacob Haley of Newton Highlands, Massachusetts" was Allen's way of saying hello to his pal Jack Haley), and on the Canin broadcast Allen knew Benny would be listening. Benny, according to Allen biographer Taylor, burst out laughing, then responded in kind on his own program. And they were off and running, going at it for over a decade and doing it well enough to convince some if not many fans of both shows that the two comedians really were blood enemies.
The Allen-Benny feud was the longest-playing, best-remembered dialogic running gag in classic radio history. The gag even pushed toward a boxing match between the two comedians and the promised event was a sellout. It also never happened, really. The pair even appeared together in films, including Love Thy Neighbor (1940) and It's in the Bag! (1945), Allen's only starring vehicle, also featuring William Bendix, Robert Benchley, and Jerry Colonna. He also starred with Oscar Levant in 20th Century-Fox' anthology film O'Henry's Full House, starring in the best filmed version to date of "The Ransom of Red Chief."
Some of the feud's highlights involved Al Boasberg, who is credited with helping Benny refine his character into (arguably) America's first stand-up comedian. Boasberg was well known behind the scenes as a top comedy writer, but he seldom received recognition in public. He worked, uncredited, on many films (including the Marx Brothers' hit A Night at the Opera). Steaming mad because of his long battles for recognition, Boasberg was said to have delivered a tirade that ended up (in slightly altered form) in an Allen-Benny feud routine:
Allen: Why you fugitive from a Ripley cartoon ... I'll knock you flatter than the first eight minutes of this program.
Benny: You ought to do well in pictures, Mr. Allen, now that Boris Karloff is back in England.
Allen: Why, if I was a horse, a pony even, and found out that any part of my tail was used in your violin bow, I'd hang my head in my oatbag from then on.
Benny's side of the feud included a tart interpretation of Allen's Town Hall Tonight show, which Benny and company called "Clown Hall Tonight." A signature element of the feud was that, whenever one guested on the other's shows, the host was liable to hand the guest the best lines of the night. (Both Benny and Allen revealed later that each man's writers consulted with each other on routines involving the feud.)
They toned the gag down after 1941, though they kept it going often enough as the years continued, climaxing on Allen's May 26, 1946 show, in which a sketch called "King for a Day," satirizing big-money game shows, featured Benny pretending to be a contestant named Myron Proudfoot on Allen's new quiz show.